Can someone sue you for money if you never signed to pay money to them when they say you made promise and you did not?

Your father in law can sue by filing the appropriate paperwork with the court. At the trial, the court will decide whether you owe the money sought. In making that determination, the court will consider any relevant evidence your father in law produces that shows you agreed to pay him the money he seeks.  The court will also consider any lawful defense you raise, such as that you never agreed to repay him, whether the debt is too old ( called the statute of limitations ) or whether the agreement needed to be in writing to be enforceable. Not all agreements need to be in writing, it depends on the particulars of his claim whether this debt needed to be in writing.   This answer is given in accordance with the laws of Virginia, and is based on the facts that are recited, and assumptions which may or may not be accurate. Accordingly, this response may not be relied upon and may not be applicable in any other state. It should not be relied on as legal advice, as that would require a detailed analysis of all of the facts involved in a specific case, not just the limited facts presented in the question.